A reciprocating Piston Air Compressor atmosphere compressor is a positive displacement compressor that runs on the crankshaft-driven piston and cylinder to compress the surroundings. … A two-stage compressor contains an additional step where the air flow is compressed by a second, smaller piston to a pressure of up to 175 PSI.
Like a small internal combustion engine, a conventional piston compressor has a crankshaft, a connecting rod and piston, a cylinder and a valve head. … As the piston movements down, a vacuum is created above it. This allows outside air flow at atmospheric pressure to drive open the inlet valve and fill the region above the piston.